Method of making metal castings.



PATENTED AUG. 4, 1903.

A. SAUVEUR. METHOD OF MAKING METAL GASIINGS.

APPLIOATION FILED JULY 10, 1902.

N0 MODEL.

THE uokms FETERS 0 morournafwumwcmu, n cy a No. 735,303.

Patented August 4, 1903.

ATENT FFICE ALBERT SAUVEUR, OF CAMBRIDGE, MASSACHUSETTS.

METHOD OF MAKING METAL CASTINGS.

srnolrloA'noiv forming part of Letters Patent No. 735,303, dated August4., 1903. Application filed July 10, 1902. Serial No. 115,035. (Nomodel.)

a specification tending down into the ingot.

My invention relates to the manufacture of metal castings, and isespecially adapted to the manufacture of steel castings, whether ofsimple ingots which are to be subjected to further mechanicalmanipulation or of more complex and finished castings for immediatecommercial use. In the description which here follows for the most partI confine myself for the purposes of simplicity and brevity to adescription of my invention as applied to the casting of steel ingots.

The common practice in making steel ingots has been to pour the moltenmetal from a large receiving vessel, which is technically called theladle, into a number of thickwalled cast-iron molds, enough being pouredinto each mold to fill it up to a prescribed level. Here the metal isallowed to cool, and

when withdrawn from the molds the blocks constitute what are technicallytermed steel ingots. The cast-iron molds in which the ingots are formedby reason of their high conductivity and large specific capacity forheat draw oi the heat of the molten metal with great rapidity, so that asolid,crust is formed at the sides of the ingot almost immediately. Thesolidificationthen proceeds inward from the sides and upward from thebottom of the mold. When the mold has been filled to the prescribeddepth, the upper surface of the ingot also begins to cool and presentlysolidifies, forming a bridge over the remaining molten metal within, sothat as the cooling and solidification proceeds upward Within the massof the ingot there is no opportunity for the top layer of metal tocollapse downward, because it has already solidified, and consequently acavity necessarily forms within the ingot a little below the top and ex-This is illustrated in Figure 1 of the drawings, hereto annexed,wherein-= i G is the cast-iron mold, shown in cross-sew -t on.

A is the ingot. b is a line showing approximately the curve ofprogression of solidification within the ingot.

0 is the top crust or bridge, and d the cavity formed by the cooling andcontraction of the metal. This cavity is technically termed a n p p ISmaller cavities and faults, such as blow- .holes, are also formed inthe casting in the neighborhood'of the pipe, and, moreover, the castingssuffer from the defect known as segregation, which consists inthecollection of impurities in the region surrounding the pipe.

The phenomenon above described is true not only of ingots, but of anysteel casting, and therefore it follows that under the present practicesome portion of any steel casting is physically unsound. Steel ingotsafter their formation in the molds are shaped and variously convertedinto finished articles by means of rolls, hammers, presses, and othermachinery known to the modern metalworker; but owing to the presence ofthe pipe and associated causes of impurity and unsoundness in the ingotthe manufacturer is obligedto discard a certain portionof' the metalfrom the top of each ingot; otherwise the unsound portion of the ingotwould carry its imperfection into the finished articles into which theingot is converted. Recognizing the inevitable imperfection in any steelcasting made according to modern practice, manufacturers in makingfinished castings of steel prevent the presence of a pipe in thefinished casting by making an additional cavity on the top of the mold,into which is poured an extra amount of metal, in which the pipe forms,leaving the casting proper free from the defect. This extra amount ofmetal is usually termed a sinking head,- and the sinking heads areremoved from the castings after the same have solidified and cooled. Bythe practice of my invention the loss occasionedby discarding the pipedparts of ingots or the sinking heads of castings will be avoided ingreat part, as will presently be understood.

My invention consists of the method of casting metal by which theformation of the cavity or pipe is entirely prevented or greatly M whichfills the next mold, and so on.

reduced, according to the degree to which my method is practiced. I

Fig. 2 of the drawings annexed hereto illustrates an apparatus by whichmy method is practiced, showing in vertical cross-section several moldsof the simple form adapted to casting of steel ingots. The molds C areplaced in series, so that the top level of metal in one mold is abovethat in the mold next below it in the series. These molds O are placedupon a platform S, which may be movable or not'to suit the convenienceof the manufacturer, and each mold is provided with the lip D, whichextends over the edge of the mold next below it in series. From a ladle,of which the lip E is shown in the drawings, the metal M is poured inmolten condition into the-highest mold of the series, and when this moldis filled the metal flows over the lip Din the stream M, filling thenext mold in series and thence forming a stream The result of the abovearrangement of the molds and the method of filling one mold by anoverflow from the next above it by series is that the metal at the topof each ingot A, which under the old practice solidified and formed acrust or bridge before the metal in the body of the ingot below it hadtime entirely to solidify, is retained in a molten condition by thepassage of the stream of metal across it, so that while the second moldin series is being filled the ingot in the first mold has time tosolidify up to the very top. Consequently when the last mold in theseries is filled and the metal is allowed to cool in this and all theothers in all except the last mold the top will be the last portion tosolidify and will then solidify in intimate solid integrity with therest of the metal in the ingot.

I have only shown three molds to illustrate my method; but it is obviousthat the series can be prolonged so as to contain very many more thanthree molds, this, however, without effecting any alteration in theprinciple of the method or any substantial change in its practice.

The gist of the invention is that I cause the top of each ingot toremain heated, and therefore liquid, while the metal below solidifies,so that the top solidifies last, thus removing all possibility of theformation of cavities or pipes. If ten molds are used in series and thepipe is confined to the last one, then the amount of loss caused by thepiping will be reduced to ten per cent. of what it is underthe presentprocess.

What I claim, and desire to secure by Letters Patent, is-

1. The method of casting metal which consists in filling a mold withmolten metal and in retarding the cooling of the upper portion of themass within the mold until the lower ALBERT SAUVEUR.

Witnesses:

JOSEPH T. BRENNAN, GRACE E. GiBBoNs.

